The invention is concerned with a process for the manufacture of roller-blinds, jalousies, safety nets, separation nets and the like, especially as applied to motor vehicles.
The manufacture of the finished article is usually carried out in such a manner, that the necessary fabric blanks required for the roller-blinds or jalousies are cut out of a master sheet and are then custom fabricated. It is necessary that the roller-blinds are furnished with a firm edging, but not so firm as to interfere with the winding operation. On this account, conventional roller-blinds were usually simply cut from a master material band, which was already trimmed to the desired width of the roller-blind. A difficulty in this is that for the various widths of windows, a plurality of different master sheets must be made. Furthermore, this means that because the full width of the fabric manufacturing machine is not fully utilized, the fabric edge, which is made by the production of the master sheet, is indeed firm, yet generally not suitable for the edge of a roller-blind. This is because the edge is damaged by needle puncture or clamping during production, impaired by subsequent additions or coatings, or may even be deformed out of line.
In the case of roller-blinds for motor vehicle windows, an additional problem arises in that non-rectangularly shaped windows must be fitted. A mass produced edge does not permit itself to be applied to windows for vehicles. These roller-blinds were, therefore, in the course of manufacture, adapted to the required edges by sewing on the necessary periphery or binding around it. This process is a very expensive step in manufacture.
Beyond this, the reinforced borders form bulges on the edges when rolled up, so that for the more thickened winding diameter, more space is required. A further danger is that the master sheet does not wind up uniformly and is distorted.
The effort has been made, to "weld" these edges, which required the use of polyvinyl chloride (PVC). PVC should no longer be used, because of the dangerous vapor developed therefrom upon burning (producing, among other things, dioxin). Another attempt has been made to substitute in this connection the better suited polyurethane, however, problems arose in weldability.
A further problem arose in the application of internal rods which were used for the stiffening of the beginning edge of the roller-blind and which serve also for activation or as a support for horizontal evenness. So called "pockets" were sewn into the master sheet, in which the rods could be inserted. This addition to the manufacture of the roller-blinds is extremely expensive. Further efforts included, in the case of layered master sheets, making such pockets by adhesives or again welding. Even this solution to the problem is very labor intensive, not to mention, that it is scarcely appropriate in its appearance.